Visitors at the Eiffel Tower were left giddy Monday as the mayor unveiled a new glass floor on Paris's best-known landmark, offering millions of tourists another perspective on the world's most-visited city.

From a vertiginous height of 57 metres (187 feet), visitors look down through a solid glass panel, offering a dizzying sensation of walking on air.

The new floor aims to turn the formerly dowdy and draughty space into as big an attraction as the viewing platform near the top of the 325-metre tower.

Previously the first floor was the least visited part of the tower, but its operators hope tourists will now linger on their way down for more breathtaking views of Paris.

The refit, which took two years, includes a display relating the life of the 125-year-old tower on seven screens, as well as a conference room.

The city of Paris, which holds a majority stake in the monument, charged architects Moatti-Riviere with creating a space that would show off Gustave Eiffel's impressive original ironwork and make it fully accessible for disabled visitors.

The renovation provided a chance to install wind turbines and solar panels to generate part of the tower's energy, and the toilets will operate partly with rainwater. "The first floor now offers an enhanced experience of the tower and of Paris," said architect Alain Moatti.

The "Iron Lady" attracts around seven million visitors a year, of which 87.5 percent are foreign tourists.

The renovation of the first floor may now be complete but work on the enormous structure built for the World's Fair of 1889 never ends. The tower has to be repainted every seven years, a job that requires 60 tonnes of paint.

"I hear that Paris has lost its attractiveness. It's not true. We are an attractive city and capable of innovation without damaging our history," said Hidalgo."Far from being a museum city," Paris is a "living museum that is in a constant state of regeneration," added the mayor.